What Is a Pending Swap and How Do You Fix It?

A pending swap is a signed transaction waiting to be included in a block; a failed swap is one that was included but reverted during execution. The difference determines your next move: a pending transaction may need a fee replacement, while a reverted transaction needs a diagnosis before you submit it again.

A swap is a specific contract call, not a token transfer that can sit halfway complete. For example, SushiSwap can route a trade through its Route Processor across one or more pools, with a minimum output encoded in the call. If execution fails that check, the transaction reverts; if it succeeds, the token movements happen atomically.

How Can You Tell Whether It Is Pending or Failed?

Check the transaction hash in a block explorer on the same network shown in your wallet. “Pending” usually means the explorer has not found the transaction in a block; “failed” or “reverted” means it was mined and execution stopped. A wallet’s spinner is not enough to tell which state applies.

On Ethereum, each account sends transactions in nonce order. Think of the nonce as a numbered ticket: if nonce 42 is still pending, a later transaction from that account generally cannot execute first. A gap can make several transactions appear stuck even when their fee settings are adequate.

For an EIP-1559 transaction, inspect maxFeePerGas and maxPriorityFeePerGas. Inclusion requires the fee cap to cover the block’s base fee plus the offered tip; a cap that no longer covers a rising base fee can leave the transaction waiting. The wallet may also show a gas limit, which caps execution work rather than setting the price per unit.

What Should You Do With a Pending Transaction?

First check whether the transaction is visible on the correct chain and whether a newer transaction from your address has already used the same nonce. If it is genuinely pending, use the wallet’s “speed up” action to submit a replacement with that same nonce and a higher fee bid. Only one transaction with that nonce can be included; if the replacement wins, the original becomes invalid.

Wallets and node mempools apply replacement rules, so the required increase varies. Raise both the fee cap and tip if the wallet asks, and keep the fee cap high enough to cover a plausible base fee while the transaction is waiting. Ethereum’s transaction FAQ describes speeding up or canceling a stuck transaction; EIP-1559 explains why the base fee and tip are separate.

To cancel, use the wallet’s cancellation action, which typically sends a zero-value transaction to your own address with the same nonce and a higher fee. Cancellation is a race, not a rollback: if the swap is included first, it executes. Confirm the explorer shows the cancellation mined before treating the nonce as cleared or submitting a new swap.

Why Did a Mined Swap Revert?

A revert means the transaction reached the contract, but a condition required for execution was no longer true. The most common swap-specific cause is minimum output: if the route’s realized output fell below amountOutMin, the call reverts rather than accepting a worse price.

For exact-input trades, the minimum is commonly calculated as quotedOut × (1 − tolerance), rounded down to token units. For example, with a quote of 100 output tokens and 0.5% tolerance, the minimum is 99.5. That percentage is a bound on adverse execution, not an estimate of gas or a guarantee of receiving the quoted amount.

Re-quote before retrying. A wider tolerance can allow more price movement, but it also permits a worse execution and can increase exposure to adverse ordering; choose it based on the pool’s liquidity and the token’s volatility, not simply to make the error disappear. Other revert causes include expired deadlines, insufficient allowance, a token-specific transfer restriction, or an execution path that no longer works. The revert reason or trace in the explorer can narrow the cause.

What Does a Failed Attempt Cost, and What Next?

A mined revert consumes gas even though the swap’s contract state changes are rolled back. The sender’s nonce is also consumed, so a failed swap does not remain pending. A transaction rejected before inclusion generally costs no on-chain execution fee, though a wallet may still display a pending record until it drops or replaces it.

Separate an approval from the swap in your history: approval is often its own transaction, so it can succeed even if the later swap reverts. Check the token allowance before approving again. On Ethereum, gas is paid in ETH; on another chain, check that network’s native gas token and fee rules, since Ethereum’s fee model and nonce behavior should not be assumed to transfer exactly.

In your place, I’d classify the hash in the explorer first, then either replace the pending nonce or re-quote and fix the specific revert condition. I would not keep resubmitting an unchanged swap: the same market movement or contract check can make it fail again.